The present invention relates to data storage devices and, in particular, to encoding identification information and other disc parameters on a magnetic disc.
In a magnetic disc drive, data is stored on one or more discs, which are coated with a magnetic medium. The magnetic medium is typically divided into a plurality of generally parallel data tracks, which are arranged concentrically with one another perpendicular to the disc radius. The data is stored and retrieved by a transducer or xe2x80x9cheadxe2x80x9d that is positioned over a desired track by an actuator arm. The actuator arm moves the head in a radial direction across the data tracks under control of a closed-loop servo system based on position information or xe2x80x9cservo dataxe2x80x9d, which is stored within dedicated servo fields.
During the fabrication and assembly process of a magnetic disc drive, a large number of magnetic discs and heads are fabricated and then tested to determine whether the magnetic properties of the discs and the heads fall within established parameters. If so, the discs and heads are selected for assembly into respective disc drives. Failing components are discarded. During a disc certification process, the recording surfaces on the magnetic discs are measured for magnetic coercivity, magnetic moment, and other physical and magnetic properties. The discs that have the desired properties are assembled onto spindles, which can be merged with corresponding head stack assemblies. Each spindle can include one or more individual discs, depending upon the configuration of the disc drive.
Similarly, the recording heads are tested before being mounted within a respective head stack assembly. Several structural and magnetic characteristics are measured, such as reader width, read signal amplitude, read signal pulse width at one-half amplitude, writer width, overwrite capability, cross-track symmetry, off-track capability and bit error rate, for example. Recording heads having the desired characteristics are mounted in respective head stack assemblies. These head stack assemblies are then merged with a respective disc pack and assembled into a disc drive housing. Each recording head is randomly paired with a respective recording surface in the disc pack.
Although each disc and recording head has been tested and found to have structural and magnetic characteristics within a desired range, the characteristics can vary between individual discs and heads and particular head-disc combinations can have less than optimal recording performance. For example, a particular recording surface may have a relatively high magnetic coercivity. If this disc is paired with a xe2x80x9cweakxe2x80x9d recording head, the resulting head-disc combination can have less than optimal overwrite capability leading to a high bit error rate. While this difficulty can be avoided by narrowing the acceptable performance ranges of each disc and head, such a solution would require higher manufacturing tolerances, reduce yield and increase manufacturing costs.
The present invention addresses these and other problems, and offers other advantages over the prior art.
One aspect of the present invention relates to a method of processing a magnetic disc prior to assembly of the disc in a disc drive storage assembly. The method includes measuring a physical characteristic of the magnetic disc and encoding an information pattern within the magnetic disc. The information pattern is associated with the measured physical characteristic.
Another aspect of the present invention relates to a method of assembling components of a magnetic disc drive. The method includes selecting a recording head for assembly into the disc drive, wherein the recording head has a magnetic characteristic. An information pattern is read from at least one of a plurality of magnetic discs prior to assembly of the disc within the disc drive. The information pattern read from the disc is associated with a magnetic characteristic of that disc. The magnetic disc is selected for assembly into the disc drive with the recording head based on a comparison of the magnetic characteristics of the magnetic disc and the recording head. The magnetic disc and the recording head are then assembled in the disc drive such that the magnetic disc and the recording head form a head-disc combination.
Yet another aspect of the present invention relates to a magnetic disc, which includes a magnetic recording surface having a physical characteristic and an information pattern encoded within the magnetic recording surface for association with the physical characteristic.